Snow particles produced from carbon dioxide are widely used in the production of frozen foods. Large bulk storage of carbon dioxide liquid is made possible by maintaining the carbon dioxide gas under proper pressure and temperature for refrigeration conditions. If storage tanks are maintained at 0.degree. Fahrenheit (-18.degree.C.), with a pressure of approximately 300 lbs. per square inch (2 MPa), the carbon dioxide is in the form of a liquid. At the point of use, the liquid carbon dioxide is converted to a mixture of fine carbon dioxide snow and vapor by rapid expansion thereof through a multitude of small orifices.
Prior art apparatus for the production of carbon dioxide snow-making employ relatively simple orifices to enable an expansion to occur of the carbon dioxide liquid feed. However, typically, prior art expansion devices or nozzles such as snow horns and orifices, create a spot impingement pattern. These are loud, and are bulky and difficult to fit into small spaces. The high velocity of the carbon dioxide snow also creates difficulty in applying an even snow blanket and can damage fragile items, such as cheese toppings on pizza or whipped toppings on bakery items.
U.S. Pat. No. 3,667,242 to Kilburn describes a structure for producing carbon dioxide snow where liquid carbon dioxide flows into an upper portion of a hollow, double-side-walled cylindrical horn. This horn has an open bottom and a closed top. A nozzle in the upper-most portion of the cylindrical horn imparts a swirling tangential movement to the snow formed in the horn.
U.S. Pat. No. 4,111,362 to Carter, Jr. describes a carbon dioxide snow making nozzle arrangement. Pairs of carbon dioxide transverse jets inject carbon dioxide into a horn region. The expanding jet mixtures of snow and vapor collide to dissipate the energy of the jets.
U.S. Pat. No. 4,287,719 uses a curved rectangular tube (J Horn) to inject vapor and a solid mixture radially along two cylinders' walls positioned at the J horn exit. The positioning injects half of the flow of CO.sub.2 along a wall of one cylinder and injects the other half along a wall of the other cylinder. This injection forms two counter rotating currents of CO.sub.2 snow. These currents fall vertically down and mix together to form large-low velocity snow.
U.S. Pat. No. 4,376,511 to Franklin, Jr. describes a carbon dioxide snow forming device wherein a manifold is positioned within a channel member and carbon dioxide snow dispenses towards the sides of the channel member. This dissipates some of the snow's kinetic energy.
U.S. Pat. No. 4,462,423 to Franklin, Jr. describes a carbon dioxide snow-forming header. Nozzles positioned along the header enable multiple regions to dispense carbon dioxide snow.
U.S. Pat. No. 4,640,460 to Franklin, Jr., describes a carbon dioxide snow-forming header containing a pair of nozzles. A supply of liquid carbon dioxide feeds inlet ends of the nozzles. In addition, applying liquid carbon dioxide to the inlet ends of the nozzle chills the supply line to reduce the temperature of the liquid carbon dioxide being supplied to the triple-point.
Attempts have been made to overcome the problems of previous agglomeration methods and designs. But, there is little prior art on the subject of fine snow agglomeration or a method of fine snow agglomeration.
For instance, U.S. Pat. No. 5,868,003 to Simas et al. describes an apparatus for producing fine snow particles in the range from 0.2 to 300 microns. This apparatus is coupled to various agglomerating devices either directly or through an intermediate pressure expansion. This device produces a stream of fine-high velocity flakes. These flakes sublimate upon contact with room temperature food objects. This technology is highly effective for rapid freezing of objects. Unfortunately, the high velocity presents problems with delicate and low-density foods. Furthermore, food suppliers desire to chill but not freeze several foods such as fresh fish. The fine flakes produced by this technology freeze the food before it can build up as a protective coating.
There is a need for an improved snow dispensing apparatus and a method that produces a highly agglomerated snow. Furthermore, such devices should produce snow particles of relatively constant particle dimensions so as to ensure even application of the particles across food or other products being cooled.
Snow dispensing nozzle apparatus can have problems with snow particles clogging the nozzles or discharge tubes. Further, the nozzles have required nearly vertical orientation relative to the surface or product to be snowed. They have also required relatively large horn discharging devices, which are not suitable for applications in physically limited spaces and for discharges into very local areas.
Fine snow dispensing nozzles have had limited application since their high velocity stream of fine particles of, for example, about 10 to 300 microns, has not been useful for some snowing applications. The fine snow particles tend to sublimate immediately on landing and do not build up on product. A jet of this fine snow that enters normal room temperature air will sublimate almost immediately as it expands away from the nozzle due to the mixing of warm air with the fine snow. Also, the high velocity flow of fine particles tends to prevent them from adhering to certain surfaces. Agglomeration devices have typically contained injectors and horns that try to uniformly expand and slow the solid vapor mixture. These types of devices do not provide for sufficient agglomeration of fine snow. Typical horns try to avoid sudden expansions and contractions in areas. This leads to plugging problems due to flow recirculation.
Accordingly, it is an object of this invention to provide improved snow dispensing nozzle apparatus that can agglomerate snow particles and provide larger snowflakes.
It is a further object of this invention to provide improved snow dispensing nozzles that can modify snow particle size, velocity and snow pattern.
It is a further object of this invention to provide an improved snow dispensing nozzle that is quiet, small, of simple design, and operates in all orientations.
It is a further object of this invention to provide an improved structure for holding an expansion member and mounting it to snow dispensing nozzles.
It is a further object of this invention to provide an improved method of agglomerating fine snow particles into larger more useful size particles.